Whether you're a recreational cyclist or hardcore bike commuter, the strongest bike locks can let you feel more confident that when you leave your bike alone, it'll still be there when you get back. To help you find the right lock for your ride, I've rounded up a selection of some of the best options out there in terms of strength. Before you pick one out, however, there are several things to consider.
The first thing to know is that there's typically a weight-to-strength tradeoff with bike locks, so the stronger and more foolproof yours is, the more heavy and bulky it will likely be. For this particular roundup, most of the locks are fairly hefty but, in some cases, I included links to more lightweight alternatives for those who are willing to sacrifice a degree of strength.
As for the best types of bike locks, there are a handful of common options to consider: chain locks, U-locks, combination locks, folding locks. Chain locks are typically the toughest and can often withstand hacksaws and chisels, but that means they're also the heaviest so they may not be the best choice for every rider. U-locks are usually the next toughest choice, as they're capable of resisting hammers and chisels (thought not hacksaws). That said, the best ones are also rather heavy. And folding locks, though not quite as strong, can often be a more compact, lightweight option.
Regardless of which design you choose, keep in mind that no lock is completely impenetrable. On top of that, it won't be effective if you don't use it properly, so make sure you know how to lock your bike up correctly. Finally, keep in mind that sophisticated thieves can swipe quick-release seats and wheels, so you may also want to invest in a locking skewer set for added protection.